[Boatanchors] R-44 Image Issue

[Richard Knoppow]

----- Original Message ----- 
From: "Joe Connor" <joeconnor53 at yahoo.com>
To: <hallicrafters at mailman.qth.net>
Cc: "boatanchors" <boatanchors at mailman.qth.net>
Sent: Tuesday, August 21, 2012 9:33 PM
Subject: [Boatanchors] R-44 Image Issue


I am working on an R-44 that has been modified quite a bit. 
I have undone most of the mods (some of which were very 
weird) and have gotten the set to play decently. It looks 
like the RF stages underwent the most modification (e.g., a 
7-pin miniature tube and socket were put in to replace the 
original 956 acorn tube).

The problem now is that on a strong local station, I get an 
image 10.5 mhz about the station's frequency. That 10.5 mhz 
is twice this receiver's 5.25 mhz IF.

Any ideas?

As always, thank you for your help.

Joe Connor

   Which band?  Note that the LO is above the signal on the 
low band and below it on the high band.  An image means the 
selectivity of the RF stages is not sufficient to suppress 
it.  It may be that these receivers had poor image response. 
The circuit looks similar to the S-36 and may be pushing the 
capabilities of the design as the S-36 does.  Adjusting the 
RF must be done carefully because all the adjustments 
interact.  That is, the RF tuning will pull the oscillator 
so both must be adjusted together by rocking the tuning.  I 
don't have a specific answer.  It would help to have an FM 
generator to sweep the RF and see what its doing. Note that 
5.25mhz is rather a low IF for the frequencies covered.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com